Texas Instruments SN74AHC245QWRKSRQ1

Overview

SN74AHC245QWRKSRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive octal bus transceiver with 3-state outputs, supporting bidirectional data flow between two 8-bit buses (A↔B) under direction control (DIR) and output enable (OE). It operates from 2 V to 5.5 V, delivers ±8 mA drive at 5 V, achieves 4 ns typical propagation delay (tPLH/tPHL), and features balanced CMOS 3-state outputs for bus isolation in vehicle infotainment and body control modules.

For engineers reviewing the SN74AHC245QWRKSRQ1 datasheet, SN74AHC245QWRKSRQ1 pinout, SN74AHC245QWRKSRQ1 application, or SN74AHC245QWRKSRQ1 equivalent, key selection criteria include automotive temperature range (–40°C to +125°C), 3-state output leakage (±2.5 µA), thermal resistance (RθJA = 67.7°C/W for RKS package), and functional mode table compliance for bus arbitration and hot-swap isolation.

Technical Context

The SN74AHC245QWRKSRQ1 implements asynchronous bidirectional bus communication using a single DIR input to select data path direction (A→B or B→A) and an active-low OE input to place all outputs in high-impedance state. Its function table defines three operational modes: enabled bidirectional transfer (OE=L), isolated high-Z (OE=H), and direction-dependent pass-through (DIR=L/H).

It uses standard CMOS inputs with ≤10 pF input capacitance and balanced CMOS 3-state outputs capable of sourcing/sinking up to ±8 mA at 5 V while maintaining VOL ≤ 0.44 V and VOH ≥ 3.8 V across –40°C to +125°C. The device includes internal clamp diodes and meets AEC-Q100 HBM Class 2 (±2 kV) and CDM Class C6 (±1 kV) ESD requirements.

Key Specifications

Pinout & Package

SN74AHC245QWRKSRQ1 is packaged in a 20-pin VQFN (RKS) with wettable flanks, 4.5 mm × 2.5 mm body size, and exposed thermal pad for enhanced PCB heat dissipation in automotive modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal bus transceiver applications.

Compared with SN74LVC245AQPWRQ1 and MC74VHC245DT, SN74AHC245QWRKSRQ1 provides optimal balance of automotive qualification, thermal performance (67.7°C/W), and 2–5.5 V flexibility-making it preferred for under-hood and ADAS applications where junction temperature margin and ESD robustness are critical.

Availability

SN74AHC245QWRKSRQ1 is available at Aetrix Electronics and suitable for automotive body control, ADAS camera bridging, infotainment expansion, electric power steering diagnostics, and telematics gateway applications requiring stable component supply across extended temperature and long product lifecycles.

Supply support for SN74AHC245QWRKSRQ1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and automotive ICs, with decades of automotive qualification expertise and ISO/TS 16949-certified manufacturing.

SN74AHC245QWRKSRQ1 belongs to TI's AHC logic family designed specifically for high-reliability automotive data routing-emphasizing wide voltage operation, robust ESD immunity, and thermal resilience in space-constrained ECUs.

FAQ

What is the maximum capacitive load SN74AHC245QWRKSRQ1 can drive while meeting all datasheet specifications?

The SN74AHC245QWRKSRQ1 is specified to drive loads ≤50 pF while maintaining guaranteed switching characteristics (e.g., tPLH ≤6.5 ns at 5 V). Driving larger capacitances increases propagation delay and may cause signal degradation; for >50 pF loads, series damping resistors or buffer staging is recommended. The SN74AHC245QWRKSRQ1 datasheet confirms this limit in Section 8.2.1.1 and Figure 8-2.

How should the OE pin be handled during power-up to ensure safe high-impedance state on SN74AHC245QWRKSRQ1?

To guarantee high-impedance outputs at power-up, OE must be held high (disabled) until VCC stabilizes. TI recommends tying OE to VCC through a pullup resistor; minimum value depends on driver sink capability but 10 kΩ is typical. This prevents bus contention during brown-out conditions. The SN74AHC245QWRKSRQ1 functional description (Section 7.1) explicitly states this requirement.

Does SN74AHC245QWRKSRQ1 support hot-swap insertion in live automotive buses?

Yes-SN74AHC245QWRKSRQ1 supports hot-swap via its 3-state outputs and integrated clamp diodes. When OE is asserted high before insertion, all pins enter high-Z with ±2.5 µA leakage, preventing bus disruption. The AEC-Q100 CDM Class C6 rating (±1 kV) further protects against insertion transients. This behavior is validated in SN74AHC245QWRKSRQ1 functional mode Table 7-1 and ESD Ratings Section 5.2.

What is the purpose of the thermal pad on the SN74AHC245QWRKSRQ1 RKS package?

The exposed thermal pad on the SN74AHC245QWRKSRQ1 RKS package provides a low-resistance conduction path from die to PCB, reducing junction-to-board thermal resistance to 73.1°C/W and enabling RθJA = 67.7°C/W. It must be soldered to a dedicated thermal plane; omitting this connection degrades thermal performance by >40%. This is documented in SN74AHC245QWRKSRQ1 Thermal Information Section 5.4.

Can unused input pins on SN74AHC245QWRKSRQ1 be left floating?

No-unused inputs (DIR, OE, or any A/B line) must be terminated to VCC or GND to prevent oscillation, excessive current draw, and latch-up. TI specifies this in Section 7.3.1 and Section 8.2.1.2, citing CMOS input structure sensitivity to slow/floating signals. A 10 kΩ pullup/pulldown resistor is recommended for uncommitted pins in the SN74AHC245QWRKSRQ1 design guidelines.